rtweets search_users function with a list of users and keyword

Question

I am trying to apply the search_users function from the rtweet package with a keyword, but only for a list of users (>300000). I am open for solutions in R or Python.

So I want to see if users from a list tweeted about a topic/keyword. If they have, I want to count one if not count zero. I am think of a loop.

Thank you